JP2584075B2 - Manufacturing method of nickel-hydrogen storage battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of manufacturing a storage battery using a hydrogen storage alloy negative electrode such as for a nickel-hydrogen storage battery.

2. Description of the Related Art Lead-acid batteries and alkaline batteries have been widely used as various power supplies. Among them, the alkaline storage battery can be expected to have high reliability, and the small battery can be used for various portable devices and the large battery can be used as an industrial device for any reason.

In this alkaline storage battery, an air electrode, a silver oxide electrode, and the like are partially mentioned as a positive electrode, but in most cases, a nickel electrode. The characteristics have been improved from the pocket type to the sintering type, and the sealing has been made possible and the use has expanded.

On the other hand, in addition to cadmium, zinc, iron, hydrogen and the like are targeted as the negative electrode. However, at present, cadmium poles are mainly used. However, a nickel-hydrogen storage battery using a metal hydride, that is, a hydrogen storage alloy electrode, has been attracting attention in order to achieve a higher energy density, and many proposals have been made for manufacturing methods and the like.

Problems to be Solved by the Invention There are two methods for producing a hydrogen storage alloy electrode: a method of sintering an alloy powder and a method of filling or applying a porous material such as foamed, fibrous, or punched metal. Hydrogen storage alloys are relatively excellent in terms of electronic conductivity, like cadmium electrodes and the like, so the possibility of non-sintered electrodes is great. That is, it is made into a paste with the binder, and this is three-dimensional or two-dimensional.
It is filled or coated on a porous conductive plate having a three-dimensional structure.
In this case, an ion-permeable resin such as polyvinyl alcohol or carboxymethyl cellulose, styrene-based gem, or the like is used as the binder. However, in any case, there is room for improvement particularly in the discharge characteristics at the beginning of the charge / discharge cycle.

Means for Solving the Problems A nickel positive electrode, a hydrogen storage alloy negative electrode, and a separator are inserted into a battery case, and after injecting an electrolytic solution, occlusion and release are repeated at least once with hydrogen gas, and then the container is sealed. In this case, the hydrogen storage alloy used for the negative electrode may be a rare earth alloy, but in particular, an alloy containing an AB ₂ Laves phase based on Zr—Ni is extremely active and is preferred for applying the method of the present invention.

Action Compared to the method of sintering hydrogen storage alloy powder in hydrogen etc., the method of filling paste into foamed or fibrous porous material, punching metal, etc. is naturally the ratio of contact with binder without electronic conductivity Is big. Therefore, special attention must be paid to maintaining the activity of the alloy. That is, it is necessary to pay attention to contamination such as oxidation of the surface of the alloy. According to the present invention, since the hydrogen storage alloy negative electrode contacts and absorbs hydrogen after being wetted by the electrolytic solution and releases it, there is no direct contact with the atmosphere after the alloy reacts with hydrogen, and the degree of contamination is greatly reduced. Is done. At the same time, the hydrogen storage alloy negative electrode has a chemical conversion effect by performing at least one storage and release of hydrogen, and by performing this treatment, it is possible to greatly improve the initial discharge capacity, which has been a problem so far. It becomes possible.

Although this hydrogen storage and release treatment is effective for any hydrogen storage alloy, alloys with excellent reactivity with hydrogen, especially those containing a Zr-Ni based AB ₂ Laves phase, are active and susceptible to oxidation. Therefore, even if hydrogen passes through the electrolytic solution and reaches the alloy, the occlusion and release are sufficiently performed, which is suitable for the present invention.

Example ZrMn which is one of AB ₂ Laves phase alloys as a hydrogen storage alloy
After mechanically pulverizing _0.4 Cr _0.4 Ni _1.2 , this alloy powder is made into a paste by adding a carboxymethylcellulose solution, filled into a foamed nickel plate having a porosity of 95% and a thickness of 1.2 mm, and pressed to obtain a capacity density of 1600 mAh / cc. Electrodes were obtained. After drying under reduced pressure, a 5% fluororesin dispersion was added to reinforce.
The obtained foamed paste-type hydrogen storage alloy electrode was cut into a width of 33 mm and a length of 210 mm, and a lead plate was attached by spot welding.

A sealed nickel-hydrogen storage battery was constructed using a known foamed nickel electrode as a counter electrode and a hydrophilic non-woven polypropylene separator. Thereafter, an electrolytic solution obtained by dissolving 25 g / 1 of lithium hydroxide in an aqueous caustic potassium solution having a specific gravity of 1.25 was injected. The battery was a subC type. The calculated capacity of the negative electrode serving as the positive electrode was set to 150%. After the battery before sealing, into which the electrolytic solution has been injected, is placed in a sealable container into which hydrogen gas can be introduced, the inside of the container is evacuated to a reduced pressure, and hydrogen is supplied at 40 ° C. at a pressure of 30 kg / cm 2. After the hydrogen storage of the hydrogen storage alloy in the negative electrode was completed, the hydrogen pressure in the container was reduced to near atmospheric pressure to release hydrogen from the hydrogen storage alloy. This operation of absorbing and releasing hydrogen is repeated three times, and the battery is taken out of the pressure vessel and finally sealed. This battery is designated as A.

Next, for comparison, a battery obtained in the same step as A and omitting the storage and release of hydrogen was added as B.

First, the initial discharge voltage and the capacity were compared. A constant current charge of 130% of the capacity at a rate of 5 hours-constant current discharge up to 0.9 V at 1.0 A was performed, and A had an average voltage of 1.20 V and a discharge capacity of 2.8 to 2.9 Ah which was almost constant after 2 cycles. Met. However, in the case of B, 8
Required ~ 11 cycles.

Next, 10 batteries were used for both batteries, and the life characteristics were compared under these charge / discharge conditions. As a result, the discharge capacity is
Even in 1000 cycles, 90% or more of the initial value was shown, whereas in B, it was 80% or less, and the performance of A was stable for a long time.

The hydrogen storage / release operation conditions using hydrogen gas vary depending on the type of hydrogen storage alloy used for the electrodes and the electrode configuration, but various conditions can be used by changing the hydrogen pressure conditions and temperature conditions.

Effect of the Invention The nickel-hydrogen storage battery according to the present invention exhibits excellent characteristics from the beginning of charge and discharge, and can maintain this for a long period of time.

Claims (2)

(57) [Claims] 1. After inserting a nickel positive electrode, a hydrogen storage alloy negative electrode and a separator into a battery case and injecting an electrolytic solution, at least one hydrogen storage and release of hydrogen into the hydrogen gas negative electrode hydrogen storage alloy is performed.
A method for producing a nickel-hydrogen storage battery, wherein the method is repeated at least twice and then sealed. 2. The method for producing a nickel-hydrogen storage battery according to claim 1, wherein the hydrogen storage alloy of the negative electrode contains an AB ₂ Laves phase based on Zr—Ni.